KR100886525B1 - Separator for fuel cell and stack for fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a separator for a fuel cell and a stack for a fuel cell using the same. The separator for fuel cells according to the present invention is a separator for fuel cells made of a composite material of graphite and a polymer, and is characterized in that a fibrous net or a carbon net is inserted as an internal structure. The separator for fuel cells according to the present invention has excellent electrical conductivity, low gas permeability, and excellent mechanical strength. In addition, there is an advantage that the manufacturing cost is low and mass production is easy.

Fuel Cell, Separator, Internal Structure, Fibrous Net, Carbon Net

Description

Separator for fuel cell and stack for fuel cell using same {Separator for fuel cell and stack for fuel cell comprising the same}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a side cross-sectional view of a separator plate for a fuel cell according to an embodiment of the present invention.

2 is a cross-sectional view schematically showing a stack for a fuel cell according to an embodiment of the present invention.

<Description of Major Symbols in Drawing>

110 Separator body 120 Internal structure

130 euros

The present invention relates to a separator for fuel cells and a stack for fuel cells including the same, and more particularly, to a separator for fuel cells and a fuel cell stack using the same, which are inexpensive, easy to mass produce, and have excellent mechanical strength. .

A fuel cell is a power generation system that obtains electrical energy through the electrochemical reaction of hydrogen or hydrocarbon-based fuel and oxidant represented by oxygen. The fuel cell obtains energy directly through the electrochemical reaction without burning the fuel, resulting in high power generation efficiency and low pollution. Research for the commercialization is actively going on.

The fuel cell includes a stack for generating electricity, a fuel supply unit for supplying fuel to the stack, and an oxidant supply unit for supplying an oxidant to the stack. In addition, the stack has a structure in which a membrane-electrode assembly and a separator are sequentially stacked, and the membrane-electrode assembly generates electricity through oxidation of fuel and reduction of oxidant.

The separator functions as a current collector that collects electrons generated in the membrane-electrode assembly, transfers fuel and oxidant delivered from the fuel supply and the oxidant supply to the membrane-electrode assembly and discharges by-products, and each membrane-electrode assembly. This function prevents fuel and oxidant from directly contacting each other. Therefore, the separator should have excellent electrical conductivity and low gas permeability. As a material satisfying such physical properties, metals such as stainless steel and aluminum and graphite have been conventionally used. However, in the case of the metal separator, there was a problem of corrosion in the acid electrolyte, and in the case of the graphite separator, the processing cost is high and it is unsuitable for mass production.

Therefore, recently, a separator using a composite material of graphite and a polymer resin has been developed, and research on it has been actively conducted. However, in the case of a separator using a graphite-polymer composite material, it is difficult to commercialize due to weak mechanical strength such as bending property. Thus, conductive reinforcement such as carbon fiber, needle-like graphite material, metal fiber or the like or non-conductive reinforcement such as natural fiber, polymer fiber, etc. is added to enhance the mechanical strength. However, the conductive reinforcing material is expensive to increase the manufacturing cost of the separation plate, in the case of non-conductive reinforcing material to reduce the overall electrical conductivity of the separation plate, there is a problem that the reliability of the metal fiber due to corrosion.

Therefore, as mentioned above, efforts to solve various disadvantages of the prior art have been steadily made in the related art, and the present invention has been devised under such technical background.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a separator for a fuel cell having excellent electrical conductivity, gas permeability, mechanical strength, and low manufacturing cost, and a fuel cell stack including the same.

In order to achieve the technical problem to be solved by the present invention described above, the present invention is a separator for a fuel cell made of a composite material of graphite and a polymer, characterized in that the fiber or carbon mesh is inserted as an internal structure Provided is a separator for a fuel cell.

The fibrous network is typically composed of synthetic fibers or natural fibers, as the synthetic fibers may be typically used polyester, acrylic or polyurethane fibers, and the like, typically as cotton or hemp This can be used. The carbonaceous net typically comprises a carbon brick, graphite or coke.

Natural graphite or expanded graphite having a particle diameter of 10 to 150 μm may be preferably used as the graphite, and the polymer resin is preferably polyethylene, polypropylene, polyvinylidene fluoride, phenol resin, epoxy resin or polyvinyl ester. Can be used.

The present invention also provides a fuel cell stack comprising the fuel cell separator according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in more detail the present invention.

1 is a side cross-sectional view of a separator plate for a fuel cell according to an embodiment of the present invention.

As shown in FIG. 1, a separator for a fuel cell of the present invention has a flow path for delivering fuel and an oxidant on both sides thereof, and an internal structure is inserted therein.

The internal structure is to improve the mechanical strength by supporting the separator, it is made of a carbonaceous net or fibrous net of the mesh structure. The fibrous network may typically include synthetic fibers or natural fibers, and as the synthetic fibers, polyester, acrylic, or polyurethane fibers may be used, and the natural fibers may be representatively cotton or hemp. And the like can be used. The carbonaceous net typically comprises a carbon brick, graphite or coke.

In the separator plate for a fuel cell of the present invention, the body portion excluding the internal structure includes a composite material of graphite and a polymer resin, and the graphite is preferably natural graphite or expanded graphite having a particle diameter of 10 to 150 μm. The polymer resin may be preferably polyethylene, polypropylene, polyvinylidene fluoride, phenol resin, epoxy resin or polyvinyl ester. Here, the content ratio of the graphite and the polymer resin constituting the body is preferably 70 ~ 90wt%, 10 ~ 30wt%, respectively, considering the electrical conductivity and mechanical strength.

In the manufacture of the separator for fuel cells of the present invention, compression molding or injection molding may be typically used. More specifically, the molding material may be injected into a mold having a separator shape and an internal structure may be inserted into the molding material. After the curing can proceed to prepare a separator.

Next, the fuel cell stack of the present invention including the fuel cell separator as described above will be described.

2 is a cross-sectional view schematically showing a stack for a fuel cell according to an embodiment of the present invention.

Referring to FIG. 2, in the fuel cell stack 300 according to the present exemplary embodiment, the end plate 370 is positioned at the outermost side, and the membrane-electrode assembly 310 and the separator plates 330a and 330b are sequentially disposed therebetween. It has a laminated structure.

The membrane-electrode assembly 310 is an electrolyte membrane 311, an anode catalyst layer 313 and a cathode catalyst layer 315 located on both sides of the electrolyte membrane as a portion that generates electricity through an oxidation reaction of a fuel and a reduction reaction of an oxidant. And gas diffusion layers 317a and 317b formed in contact with the anode catalyst layer 313 and the cathode catalyst layer 315.

In the membrane-electrode assembly 310, the anode catalyst layer 313 is where the oxidation reaction of the fuel occurs, and all of the catalysts commonly used in the anode catalyst layer of a fuel cell may be used. Platinum-based catalysts are mainly used. Representative examples of platinum-based catalysts include platinum, ruthenium, osmium, platinum-ruthenium alloys, platinum-osmium alloys, platinum-palladium alloys, or platinum-transition metal alloys. The above can be mixed and used. On the other hand, the transition metal in the platinum-transition metal alloy is a single metal or two or more consisting of one element selected from the group consisting of Ga, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn Transition metal alloys formed.

The cathode catalyst layer 315 is a place where a reduction reaction of an oxidant occurs, and all catalysts commonly used in the cathode catalyst layer of a fuel cell may be used. The platinum catalysts used in the anode catalyst layer 313 may be equally used in the cathode catalyst layer 315.

The electrolyte membrane 311 transfers the hydrogen ions generated by the oxidation of the fuel in the anode catalyst layer 313 to the cathode catalyst layer 315, and separates the anode catalyst layer 313 and the cathode catalyst layer 315 to form a fuel or oxidant therebetween. As a function of preventing the inflow of water, all of the ion transport materials commonly used in the electrolyte membrane of the fuel cell may be used. Representative examples include polymer resins having ion exchange groups such as sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, and derivatives thereof in the side chains. Mid polymer, polyetherimide polymer, polyphenylene sulfide polymer, polysulfone polymer, polyether sulfone polymer, polyether ketone polymer, polyether-ether ketone polymer or polyphenylquinoxaline polymer Can be used.

The gas diffusion layers 317a and 317b serve to transfer fuel or oxidant delivered from the separator 330 to the anode / cathode catalyst layers 313/315, and the gas diffusion layers 317a and 317b. Any conductive substrate commonly used in the art can be used. Representative examples include carbon cloth, carbon paper, and carbon felt.

The electricity generating unit has an edge of the anode / cathode catalyst layer 313/315 and the gas diffusion layers 317a and 317b to prevent leakage of fuel or oxidant from the anode / cathode catalyst layers 313/315 and the gas diffusion layers 317a and 317b. The gasket 350 may be further provided. However, this is only one embodiment and can prevent the leakage of fuel or oxidant in various ways.

The end plate 370 is positioned at the outermost part of the stack to fasten one or several stacked electric generators, and includes an inlet for inlet of fuel and an oxidant and an outlet for discharging by-products.

The fuel cell stack of the present invention as described above constitutes a fuel cell together with a fuel supply unit supplying fuel to the stack and an oxidant supply unit supplying an oxidant to the stack.

Optimal embodiments of the present invention described above have been disclosed. Although specific terms have been used herein, they are used only for the purpose of describing the present invention in detail to those skilled in the art, and are not used to limit the scope of the present invention as defined in the meaning or claims.

As described above, the separator for fuel cell according to the present invention has excellent electrical conductivity, low gas permeability, and excellent mechanical strength. In addition, there is an advantage that the manufacturing cost is low and mass production is easy.

Claims (8)

Main body consisting of 10 to 30% by weight of polymer resin and 70 to 90% by weight of graphite having a particle diameter of 10 to 150 µm and Incorporated into the network structure inside the main body is made of an internal structure that imparts mechanical strength, The inner structure is a separator for a fuel cell, characterized in that the fibrous or carbonaceous net. The method of claim 1, The fibrous network separator plate for a fuel cell, characterized in that comprises a synthetic fiber or natural fiber. The method of claim 2, The synthetic fiber is a separator for a fuel cell, characterized in that selected from the group consisting of polyester, acrylic and polyurethane fibers. The method of claim 2, Separation plate for a fuel cell, characterized in that the natural fiber is cotton or mine. The method of claim 1, The carbonaceous net is a fuel cell separator, characterized in that comprises a carbon brick (carbon brick) or coke. delete The method of claim 1, The polymer resin is a separator for a fuel cell, characterized in that selected from the group consisting of polyethylene, polypropylene, polyvinylidene fluoride, phenol resin, epoxy resin and polyvinyl ester. A fuel cell stack comprising a separator for fuel cells according to any one of claims 1 to 7.

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